Effect of V, Nb and Ti Addition and Annealing Temperature on Microstructure and Tensile Properties of AISI 301L Stainless Steel

摘要

The effects of V, Nb and Ti additions and the annealing temperatures on the microstructure and tensile properties of AISI 301L stainless steel have been investigated. The grain size of 0.9 μm was obtained by adding 0.5 mass% V with the annealing at 850℃ for 30 s, while those of original 301L annealed at 850 and 1 000°C were 2.7 and 9.8μm, respectively. The grain size decreased as V and Nb increased up to 0.5 and 0.1 mass%, respectively, with the increase in the number density of the precipitate particles. The additions of V over 0.5 mass%, Nb over 0.1 mass% and Ti did not affect the grain size because these additions hardly contributed to the increase in the particle number density. The grain size also decreased with the decrease in the annealing temperature from 1 000 to 850℃. These grain refinements were achieved mainly by the pinning effect of the precipitates and the decrease in the mobility of the grain boundary itself with the decrease in the annealing temperature. The difference of the pinning effect by V, Nb and Ti was explained by the gap of the solubility limit of these elements between the temperatures of the solution treatment and annealing. 0.2% proof stress increased from 400 to 750 N/mm~2 as the amount of V and Nb increased and as the annealing temperature decreased. These strengthenings were explained mainly by the grain refinement in accordance with the Hall-Petch relationship and the influences of other strengthening mechanisms were estimated as quite small.